Perception II Flashcards
What are the tasks of mid-level vision?
(recap)
-> Grouping elements belonging together
- Similarity
- Enclosure
- Proximity
-> Distinguishing between not belonging elements
-> Inferring outside using top-down knowledge
-> Avoid accidental combinations of features
-> Resolve ambiguity to come to a single interpretation
What are sum questions regarding object recognition?
(object perception)
How do we recognize different images as the same object?
How does your visual system move from points of light to whole entries in the world.
What is the template matching theory?
(object perception)
Template theory matching
-> basic approach to human pattern recognition
-> every perceived object is stored as a template
-> incoming sensory infromation is compared to these
templates
=> all sensory inputs are compared to multiple
representations of an object to form a conceptual
understanding
What types of pathways of the brain for visual perception exist?
(object perception)
Dorsal Pathway (WHERE)
-> identifying the object’s location
-> includes Parietal lobe
Ventral Pathway (WHAT)
-> identifying an object
-> include the temporal lobe
What is the approach of the dissociation logic for perception and attention?
(object perception)
complex system can logically be deduced from malfunctions
-> damage to different areas of the brain cause very different deficits
- specific brain area for specific function concludable
-> Brain Ablation method
- scientists damage specific brain area
- controlled damage for clearer conclusions
What are the results of Brain Ablation as performed by Ungerleider & Michkin (1982)?
(object perception)
Brain Area Removed | Effect on Perception
————————————-|—————————————–
Parietal Lobe | Landmark discrimination
————————————-|——————————————
Temporal Lobe | Object discrimination
Which 2 kind of dissociations does the dissociation logic hold?
Single dissociation
(= one function is lost, another remains)
example
-> Monkey A has damage to temporal lobe
-> Monkey unable to identify object (what) but can still
identify locations (where)
=> what and where rely on different mechanisms
(does not mean complete independence)
Double dissociation
(= two individuals with different damage and opposite
deficits)
example
-> Monkey A with temporal lobe damage and Monkey B with parietal lobe damage
-> Monkey A with intact parietal lobe and Monkey A with intact temporal lobe
=> what and where streams must have different
mechanisms AND operate independently from
each other
What are causes of the disruption of the ventral pathway?
(object perception)
WHAT-pathway
Visual Agnosia
-> loss of ability to recognize objects
-> preserved ability to navigate, reach
-> bilateral damage to occipital/temporal lobes
-> prosopagnosia (specific to face recognition)
Simultanagnostic
-> normal visual fields, yet act blind
-> perceives only one stimulus at a time
(single word or object)
Prosopagnosia
-> inability to recognize faces
(including one’s own)
-> cannot recognize person from face
-> knows a face is a face
-> can recognize objects
-> can discriminate faces from each other
What are causes of the disruption of the dorsal pathway?
(object perception)
WHERE-pathway
Optic Ataxia
-> cannot use vision to guide movement
-> unable to reach for item
How is face recognition a special case of object recognition?
(object perception)
Faces
(= special type of object due to emotional and social
importance)
Face Inversion Effect (FIE)
-> more difficult to process when seen upside down
Moony Faces Test
Craig M. Mooney
-> showing participants a series of black and white
distorted photographs
-> they must interpret to form a coherent mental picture
What is the Thatcher Illusion?
(object perception)
Thompson, 1980
Thatcher Illusion
= illustrates that when a face is turned upside-down its components (eyes, nose, mouth) are processed individually
-> we are very sensitive to the configurations of these
components, but only for upright faces
=> the whole is more than the sum of its parts
(getalt psychology)
=> demonstrates how detailed our brain analyzes
configurations of faces
(up to 5000 faces recognizable)
What is the connection between the inferior temporal cortex and face recognition?
(object perception)
Inferior Temporal Cortex
-> Firing rate increases when a face is seen
-> little firing rate when a face like object is seen
=> Fusiform Face Area (FFA)
Greebles
Gauthier et al. 1999
-> face like shapes can be trained to increase firing rate on the FFA
How are neurons and the environment connected?
(environmental influences)
Neurons and the environment
-> some neurons respond to things that occur regularly in the environment
-> tuning to respond best to what we commonly
experince
- horizontals and verticals
- experience-dependant plasticity
What are mirror neurons?
(environmental influences)
= neurons that respond the same way when observing someone else perform an act as if one actually perfoms the act oneself
-> located in the premotor cortex
=> might be to help understand another person’s action and react appropriately to them
(learning through imitation)
What is the importance of context in object perception?
(scene perception)
Objects are perceived in Context
-> stand out when out of Context
